Much has been learned in recent years concerning the microbial and biochemical composition of plaque, and its importance in the etiology of dental caries is well documented. However, little is known still about how plaque is formed. Two important aspects of plaque formation are the highly specific nature of bacterial colonization on the tooth surface, and the key role that certain salivary proteins play in interbacterial attachment, or aggregation, in the development of the enamel pellicle, and in the adhesion of specific bacteria to the surface of the tooth. Our objective is to study the basic molecular interactions that give rise to the adhesive phenomena and to apply these findings to the modification of plaque and the processes that contribute to its formation. The proposal outlines studies for the purification and characterization of two specific salivary aggregating factors and the surface receptors from strains of Streptococcus sanguis and S. mitis. Enzymes and group specific reagents will be used to determine macromolecular structure and the basic mechanisms of interaction. The purified substances and appropriate reagents will be used in experiments to modify adhesion and plaque formation in vivo. BIBLIOGRAPHIC REFERENCES: E. Liberman and S. Kashket, "Teichoic acid as a receptor for Con A in Streptococcus sanguis", J. Dent. Res. 55, Abstracts 54th Meeting IADR (1976). Abstracts: K.M. Guilmette and S. Kashket, "Enzymatic treatment of salivary aggregating factors". J. Dent. Res. 55, Abstracts 54th Meeting IADR (1976).